1. Field
This document relates to a liquid crystal display and a method for driving the same.
2. Related Art
A liquid crystal display periodically inverts the polarity applied to liquid crystal molecules to reduce direct current afterimages and flicker. Well known in the art such as an inversion driving method includes a variety of methods such as dot inversion shown in FIGS. 1 and 2 and column inversion shown in FIG. 3. In FIGS. 1 through 3, the x-axis is a horizontal direction which is parallel to a gate line (or scan line) of a liquid crystal display panel, and the y-axis is a vertical direction which is parallel to a data line of the liquid crystal display panel. In FIGS. 1 through 3, “FR1” is a first frame period, and “FR2” is a second frame period.
In the dot inversion method as shown in FIG. 1, the polarity of a data voltage charged in liquid crystal cells is inverted every 1 dot in horizontal (x-axis) and vertical (y-axis) directions for each frame period. 1 dot is equal to 1 liquid crystal cell or 1 subpixel, which is the smallest unit for writing a data voltage to the screen. In the dot inversion method as shown in FIG. 2, the polarity of the data voltage charged in the liquid crystal cells is inverted every horizontal 1 dot and every vertical 2 dots. In the dot inversion method, as shown in FIG. 2, the polarity of the data voltage charged in the liquid crystal cells is inverted for each frame period. In the dot inversion method shown in FIGS. 1 and 2, any flicker or difference in luminance is not observed in the horizontal and vertical directions and therefore high picture quality can be achieved. However, the power consumption and heat generation of a data driving circuit are high because the polarity of the data voltage supplied through a data line is inverted many times.
In a column inversion method shown in FIG. 3, the polarity of a data voltage charged in liquid crystal cells is inverted every 1 dot in a horizontal direction but not in a vertical direction. In the column inversion method, as shown in FIG. 3, the polarity of the data voltage charged in the liquid crystal cells is likewise inverted for each frame period. In the column inversion method, the polarity of the data voltage supplied through a data line is not inverted during one frame period. Thus, the power consumption and heat generation of a data driving circuit are low, and this method is relatively excellent in picture quality.
Unless the polarity of a data voltage continuously supplied through the same data line is changed, the amount of data voltage change is small, which shortens the response time of the liquid crystal cells. On the other hand, when the polarity of the data voltage continuously supplied through the same data line is inverted, the amount of data voltage change is large, which lengthens the response time of the liquid crystal cells. Due to this difference in response time, the conventional inversion methods cause a luminance difference between neighboring liquid crystal cells.